[turbofan] Introduce JSCreateLowering for optimizing JSCreate nodes.

src/type-cache.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_TYPE_CACHE_H_
 #define V8_TYPE_CACHE_H_
 
 #include "src/types.h"
 
 namespace v8 {
@@ skipping 94 matching lines @@
   // The JSArray::length property always contains a tagged number in the range
   // [0, kMaxUInt32].
   Type* const kJSArrayLengthType =
       CreateNative(Type::Unsigned32(), Type::Tagged());
 
   // The String::length property always contains a smi in the range
   // [0, String::kMaxLength].
   Type* const kStringLengthType =
       CreateNative(CreateRange(0.0, String::kMaxLength), Type::TaggedSigned());
 
-  // When initializing arrays, we'll unfold the loop if the number of
-  // elements is known to be of this type.
-  Type* const kElementLoopUnrollType = CreateRange(0.0, 16.0);
-
 #define TYPED_ARRAY(TypeName, type_name, TYPE_NAME, ctype, size) \
   Type* const k##TypeName##Array = CreateArray(k##TypeName);
   TYPED_ARRAYS(TYPED_ARRAY)
 #undef TYPED_ARRAY
 
  private:
   Type* CreateArray(Type* element) { return Type::Array(element, zone()); }
 
   Type* CreateArrayFunction(Type* array) {
     Type* arg1 = Type::Union(Type::Unsigned32(), Type::Object(), zone());
@@ skipping 16 matching lines @@
     return Type::Range(min, max, zone());
   }
 
   Zone* zone() { return &zone_; }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TYPE_CACHE_H_